Convert Helix instancing feature flag to a Preference Setting

[saintentropy]

Purpose

Convert the Helix Instancing feature flag to a Preference Setting.

Declarations

Check these if you believe they are true

• [x] The codebase is in a better state after this PR
• [x] Is documented according to the standards
• [x] The level of testing this PR includes is appropriate
• [x] User facing strings, if any, are extracted into *.resx files
• [ ] All tests pass using the self-service CI.
• [ ] Snapshot of UI changes, if any.
• [ ] Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• [ ] This PR modifies some build requirements and the readme is updated
• [ ] This PR contains no files larger than 50 MB

Release Notes

Reviewers

(FILL ME IN) Reviewer 1 (If possible, assign the Reviewer for the PR)

(FILL ME IN, optional) Any additional notes to reviewers or testers.

FYIs

(FILL ME IN, Optional) Names of anyone else you wish to be notified of

[github-actions[bot]]

UI Smoke Tests

Test: success. 2 passed, 0 failed. TestComplete Test Result Workflow Run: UI Smoke Tests Check: UI Smoke Tests - net6.0

[github-actions[bot]]

UI Smoke Tests

Test: success. 2 passed, 0 failed. TestComplete Test Result Workflow Run: UI Smoke Tests Check: UI Smoke Tests - net8.0

[github-actions[bot]]

UI Smoke Tests

Test: success. 2 passed, 0 failed. TestComplete Test Result Workflow Run: UI Smoke Tests Check: UI Smoke Tests - net6.0

[github-actions[bot]]

UI Smoke Tests

Test: success. 2 passed, 0 failed. TestComplete Test Result Workflow Run: UI Smoke Tests Check: UI Smoke Tests - net8.0

[QilongTang]

@saintentropy @aparajit-pratap Not sure what's the plan for this, I will move this to 3.1 milestone so we can close the 3.0 milestone on Github to wrap up the release.

[QilongTang]

Hi @saintentropy @aparajit-pratap Please confirm this PR's state and Jira task?